Significant research and development is being performed to generate robots (e.g., humanoid, quadruped, etc.) that are capable of functioning on various types of terrain. The functions that a robot is capable of fulfilling depend on its ability to traverse varying terrain (e.g., stairs, hills, sand, etc.). Robots that are unable to move without falling over risk harming people, damaging property, and damaging the robot itself.
Multiple strategies have been developed to reduce the risk of robots falling by improving the stability of robotic walking. One particular method is to adjust the trajectory of the robot in such way that the Zero Moment Point (ZMP) (i.e., the point on the ground where the moment of the bearing axis and the moment of the azimuth axis are zero) is included in the robot's support polygon. This strategy is insufficient to ensure stability under all conditions, notably on uneven terrain or where the robot may be bumped or pushed by third parties.
Another strategy for wheeled robots is to use an inverted pendulum or a gyroscope with the pivot point attached to one or more wheels rolling on the ground. If the robot leans forward, a motor spins in the same direction, matching the balance of the robot. However, gyroscopes resist changes in direction due to precession, which makes it difficult to compensate for changes in terrain.